1. Technical Field
This invention relates to accessory modules for use in connection with an electrical system of a motor vehicle, and more particularly to a module for providing a connecting point to a serial data bus of an onboard computer of a motor vehicle to allow communication between the serial data bus and an external accessory device.
2. Discussion
As computers and other sophisticated electronic devices become more powerful and more compact, the opportunity increases to use such devices in motor vehicles such as automobiles and trucks. In particular, the increasing availability of lap top or palm top computers is accelerating this trend.
In present day motor vehicles an on-board computer, typically known in the industry as an electronic control module (ECM), is used which is capable of controlling a large number of various electronic components of a vehicle. This is facilitated, in part, by a data bus which is used to transfer information between the ECM and the various electronic sub systems of the vehicle. The data bus of the vehicle carries a large amount of useable electronic information relating to the operation of the vehicle and its numerous electronically controlled subsystems.
In view of the large amount of useful information that is transmitted over the vehicle's data bus, it would be highly desirable to provide some form of relatively inexpensive apparatus which directly interfaces with the vehicle's data bus and allows communication of information from the vehicle's data bus to an external accessory device such as a lap top computer, an electronic compass, etc., and which also is capable of allowing a limited amount of information to be transferred between the device and the vehicle's data bus. In this matter, the information on the vehicle's data bus could be used to enhance operation of the external accessory devices, such as enhancing the operation of an application program running on a lap top computer. Conversely, in certain applications, the operation of the vehicle could be enhanced by information provided to the vehicle data bus by the external device. Also, by providing a convenient point to make electrical connections, such an external device as a lap top computer or an electronic compasses could be quickly and easily coupled and uncoupled to the vehicle's data bus without special tools or time consuming procedures.
Accordingly, it would be highly desirable to provide an apparatus which is capable of allowing an external device such as a lap top computer, an electronic compass, etc., to be quickly and easily interfaced to a vehicle's data bus so as to be able to receive information from the data bus or to transmit information to the data bus.